BiMOx Semiconductors as Catalysts for Photocatalytic Decomposition of N2O: A Combination of Experimental and DFT+U Study

A series of Bi-based semiconductor photocatalysts (BiVO4, Bi2MoO6, and Bi2WO6) with different crystallite structure and morphology are designed and controllably constructed by a facile hydrothermal method. Their catalytic activities are investigated for N2O photocatalytic decomposition for the first time. It is found that monoclinic BiVO4 exhibits a higher photocatalytic activity than orthorhombic Bi2MoO6 and Bi2WO6 because of its stronger absorption ability for visible light and higher separation efficiency for photogenerated charge carriers. N2O conversion reaches 27.1% over monoclinic BiVO4 at 25 °C after 12 h of irradiation. The formation of oxygen vacancies on BiMOx leads to the creation of excess electrons, which could be beneficial for the conversion of O on N2O into O2– and thereafter promote the decomposition of N2O. Moreover, DFT+U calculation is used to clarify the relationship between the oxygen vacancy formation energy and electronic properties of the catalyst at the microscopic level, as well as the reaction pathway of N2O decomposition over these photocatalysts, is illustrated.